This invention relates to apparatus for transmitting pulling motion from along a generally vertical axis to along a generally horizontal axis, and more particularly, to a vertical pull apparatus typically including a support which is positioned in a generally vertical position. A cable-engaging mechanism provided on the support engages a cable and defines a generally vertical cable segment and a generally horizontal cable segment in the cable. A first cable-gripping element and a second cable-gripping element on the support alternately and repeatedly grip and release the vertical cable segment of the cable. At least one of the cable-gripping elements is adapted for gripping and pulling the vertical cable segment of the cable, such that the horizontal cable segment is pulled horizontally.
Underground water, gas, sewer and other utility pipes typically require replacement after an extended period of use, frequently due to corrosion or damage to the pipes. Usually, digging trenches to expose the damaged pipes for replacement is undesirable since this frequently requires destruction of streets, sidewalks, parking lots or lawns, which is unsightly and expensive. To avoid these problems, various techniques and apparatuses have been devised to destroy the pipe in need of replacement and draw a new pipe into place without having to excavate trenches for the operation. Generally, the techniques involve excavating the ground at both ends of the pipe to be replaced and positioning a hydraulic pulling device of selected design in one of the excavations and a cutting tool at the opposite end of the pipe in the other excavation. A cable is extended from the pulling device, through the pipe and attached to the cutting tool at the opposite end of the pipe. As the hydraulic pulling device is operated to pull the cutting tool against the pipe, a pneumatic hammer may be used to repeatedly strike the cutting tool against the pipe, and the combined pulling action of the pulling device and striking action of the hammer on the cutting tool causes the tool to migrate and progressively cut and burst the pipe along the entire length of the pipe. A replacement pipe is typically attached to the cutting tool such that the replacement pipe is drawn into position behind the cutting tool as the cutting tool bursts the old pipe. Under circumstances in which the hydraulic pulling device must be placed in a manhole at one end of the pipe, the narrow confines of the manhole render difficult adequate positioning of the hydraulic pulling device for the pipe bursting and replacing operation.
A variety of devices are known in the art for transmitting a vertical or angled pulling motion into a horizontal pulling motion. Typical of these are the devices detailed in U.S. Pat. Nos. 4,318,835; 4,457,647; 4,685,831; 5,173,009; 5,192,165; 5,302,053; 5,328,297; 5,403,122; 5,642,912; 5,709,503; 6,109,832; and 6,244,783.
Devices of various design are known in the art for bursting or re-rounding underground pipes. Patents of interest in this regard include U.S. Pat. Nos. 4,457,647; 4,634,313; 5,173,009; 5,192,165; 5,205,671; 5,302,053; 5,328,297; 5,403,122; 5,642,912; 5,709,503; 5,782,311; 5,785,458; 6,092,553; 6,109,832; 6,129,486; and 6,244,783.
An object of the present invention is to provide a vertical pull apparatus for transmitting a generally vertical pulling motion into a generally horizontal pulling motion.
Another object of this invention is to provide a vertical pull apparatus which is capable of a variety of applications.
Still another object of this invention is to provide a vertical pull apparatus including a support for positioning in a generally vertical position; a cable-engaging mechanism provided on the support; a cable engaging the cable-engaging mechanism such that the cable-engaging mechanism defines a generally vertical cable segment and a generally horizontal cable segment in the cable; and first and second cable-gripping elements provided on the support for repeatedly and alternatively engaging the vertical cable segment of the cable, wherein at least one of the cable-gripping elements grips and pulls the vertical cable segment to pull the horizontal cable segment of the cable along a horizontal axis.
These and other objects of the invention are provided in a vertical pull apparatus for converting a vertical pulling action to a horizontal pulling action, which vertical pull apparatus typically includes a support for positioning in a generally vertical position. A cable-engaging mechanism is provided on the support, which cable-engaging mechanism engages a cable and defines a generally vertical cable segment and a generally horizontal cable segment in the cable. A first cable-gripping element and a second cable-gripping element on the support alternately and repeatedly grip and release the vertical cable segment of the cable. At least one of the cable-gripping elements is adapted for gripping and pulling the vertical cable segment of the cable along a vertical axis, such that the horizontal cable segment is pulled along a horizontal axis.